The present invention relates to an electrolytic bath that the working electrode is composed of multi-rotating disk electrode (hereinafter refered to as multi-RDE) and solid polymer electrolyte (SPE) electrode, more particularly to a novel multi-rotating disk electrode and solid polymer electrolyte electrode type electrolytic bath in which the surface area of electrode is increased and the agitation effect in solution is improved by multi-RDE, while the migration of reactants and reaction product toward other chambers is prevented by utilizing SPE electrode, whereby high reaction yield is obtained under lower electrolytic voltage.
Various kinds of electrolytic bath utilized for the industry have been known, and the typical electrolytic baths for the industry include, for example, capillary gap electrolytic bath, Swiss roll electrolytic bath, electric charge layer electrolytic bath, fluid layer electrolytic bath, slurry electrolytic bath, gas diffusion electrolytic bath, SPE electrolytic bath and rotary electrode electrolytic bath [refer to Colin Oloman, AICHE Symposium Series 229, Vol, 79, 68 (1983) and Hiragame Koryo and Nishiguni yoozo, Chemical Industry, 36(10), 721(1985) ].
The respective features of the above mentioned baths are described briefly in the followings.
Firstly, tank type electrolytic bath is an electrolytic: bath of the most fundamental form in which a plurality of positive electrodes and negative electrodes are mounted on the interior of electrolytic bath whereby current distribution is uniform, while it has advantage that the workability is better and repairing is easier, but there has been some problems that it is unsuitable for electrolytic organic synthesis since the production quantity can not be increased and mixing of solution is insufficient.
Next, filter press type electrolytic bath is composed of a plurality of positive electrodes and negative electrodes neighbouring each other and thereby having an advantage that electrode area can be increased and distance between electrodes can be reduced, and it is used much for industrial purpose, because the production quantity can be increased, however it has disadyantages that their assembling and repairing works are complicated, and when the solid substance is produced within electrolytic solution, the said solid substance blocks the inlet of electrolytic solution.
Capillary gap electrolytic bath is of the type that the distance between electrodes is minimized so that the electrolytic solution may be flowed in high speed, which has property suitable for non-aqueous solution electrolyte of single phase, but having problems that it is not suitable for multiple electrolyte and requiring more pump driving power.
Swiss roll electrolytic bath is of the type that the isolating film having a good flexibility and electrode as well as spacer are stacked to assembly in the sandwitch manner, which exhibits disadvantage that the current density cannot be increased much more.
Electric charging layer electrolytic bath is a matter that the particle electrode is charged and thereby the surface area of electrode is extremely increased, but has a problem in contacting between the electrode and the power supply source.
Fluid layer electrolytic bath is a matter that the particle electrode is mounted in fluidized state, it is unsuitable for multiple electrolyte and has also a problem in contacting between the electrode and the power supply source.
SPE electrolytic bath is of the type that electrodes are formed on one side or both sides of ion exchange membrane, which includes an advantage that the supporting electrolyte is not necessary and the electrolysis is possible even in organic solvent of non-polarity, but has problems that the manufacturing of electrode is not easy and the material migration is not suitable for the reaction of the rate determining step.
RDE is of the type that the electrode rotates, which is used much for laboratory purpose, and since the material migration speed can be considerably increased and, at the same time the material migration phenomenon is well arranged theoretically, the RDE is used much for examining the reaction mechanism of the electro chemical reaction, however, since only one side of electrode is used, the surface area of the electrode is relatively small, and in case of being used for the industrial purpose, the high speed rotation is impossible so that the agitation in solution can not be carried out sufficiently, it is almost not used for the industrial electrolytic bath.